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As a leading practitioner, and speaker, David Landwehr, D.D.S., M.S. serves as a frequent teacher at events focusing on endodontics and oral pathology. Dr. Landwehr’s ongoing work as an opinion leader has positioned him at the forefront of modern endodontic treatment. Dr. Landwehr’s teaching focuses on techniques used daily in his clinical practice that are efficient, evidence based and attainable for any practitioner.
A Wisconsin native, Dr. Landwehr studied as an undergraduate at the University of Wisconsin-Madison and went on to earn his D.D.S. at the University of Minnesota. From there, he earned an M.S. degree and certificate in Oral and Maxillofacial Pathology at The Ohio State University followed by specialty training in Endodontics at the University of Michigan. Since returning to Wisconsin in 1999, Dr. Landwehr has provided exemplary care to patients in a private practice setting
VIDEO-DUwHF #1089 David Landwehr
AUDIO-DUwHF #1089 David Landwehr
Howard: It was just a huge honor for me today to be podcast interviewing David Landwehr DDS MS serves as a frequent teacher at events focusing on endodontics and oral pathology. His ongoing work as an opinion leader has some positioned him at the forefront of modern endodontic treatment. Dr. Landwehr teaching focuses on techniques used daily in his clinical practice that are efficient evidence-based and attainable for any practitioner. A Wisconsin native Dr. Landwehr studied as an undergraduate at the University of Wisconsin Madison and went on to earn his DDS at the University of Minnesota from there he earned an MS degree and certificate in oral and maxillofacial pathology at the Ohio State University followed by specialty training in endodontics at the University of Michigan. Since returning to Wisconsin in 1999 he has provided exemplary care to patients in private practice setting. It really is a huge honor to have you come on the show I'm a big fan of yours and I know my homies like the back of my hand and half of them hate molar endo and what would you say to even in dental school I mean 25 percent of our podcast listeners are still in dental school shoot me an email Howard@dentaltown.com tell me your age, where you're at. What would you tell kids in dental school that already have made up in their mind that they hate molar endo?
David: They need to change that mindset because I know if I can do it anybody can do it. Now what's the difference between me and them I've done it for 20 years so I've got a little bit of experience and I've made all the mistakes, you've got to be willing to make some mistakes okay, there's a learning curve there's a process to it best to learn and do those mistakes create those iatrogenic issues out of the mouth okay do some practice teeth. There's no reason that you got to jump right into the most complicated molar anatomy straight away in the mouth, access into some teeth cut through some teeth see where the canals and our access some canals out of the mouth take that experience in that skill set back into the mouth okay. So doing some things out of the mouth and getting some level of experience and and by all means in dental school do as much as you possibly can push the limit that's the time to get the experience that's what you're paying for that's why I do there.
Howard: but it's it's literally frightening though I mean they're coming out of these private schools where they pay $100,000 a year tuition they've got three hundred fifty to four hundred thousand dollars of student loans and they tell me that they've done three root canals and they were all single canal teeth.
David: Right and three for some as many dumb schools they're getting out doing one two some schools are giving credit for watching a resident do a root canal and from my experience that is not a good way to learn okay you've got to be in the trenches doing this is what we do every day all day this is why we can make it look so simple. The other thing for you know the young clinician as they get out partner up with an endodontist you're not it's not realistic for you to think that you're going to immediately out of school do every case that presents to your office partner up build a relationship send them a bunch of cases early on in your career when you're inexperienced when you're not comfortable but that comes with a caveat get into their office see how they treat patients see what they do take those techniques bring them back to your office now you're gonna start to see okay I can do this one this one's within my realm this is my skill set send out the ones that are gonna take two hours three hours where the patient is going to say well I'm never gonna do that again because then they're gonna start looking for a new dentist. When people have bad experiences they love to tell people about bad experiences but when it goes smoothly the way it's designed to go they're not as apt to tell as many people. So I grew up with an endodontist and and if that ended on us doesn't want you in their office and doesn't want to share their knowledge and skill set with you find a new one that does.
Howard: Yeah I mean a lot of them thinking fear and scarcity and and go ask an orthodontist for help on an Invisalign case or ask to watch and a periodontist place an implant they're like no and it's like why I'm you know it was still a great sell called because you just realized this guy said no and thinks in fear and scarcity and the next one will think in hope growth of abundance and form a relationship with you and but they're so shy. By the way I have to give it to you, you have the best name in endo, obtra.com obtra.com that is the coolest damn name. I almost went to podcast just for that damn name Obtra it is it's just amazing and I don't want to tell them it's your email address too because then they'll figure even that out.
David: That has been my email handle since the 90s.
Howard: Oh my gosh so going back to the 90s on you've been doing this for two decades what's really what would significantly change in 20 years of technology from when you started this 20 years ago?
David: Well when I started we were on the cutting edge of rotary endodontics, so taking it from doing purely hand files to now doing some mechanical instrumentation but mechanical instrumentation after significant hand filing because the quality of the metals that were that we were using in first generation nickel titanium they just weren't out to snuff not anything compared to where we are today. So the ability to mechanically instrument a root canal has evolved tremendously it was initially multiple instruments multiple tapers five six seven instruments to create the final shape and now I can create that final shape in my clinical practice using two maybe three instruments in it you know I'm no different than any of anybody else I'm a private practice clinician I'm cheap I'm lazy you know I want to be effective I want to be efficient if I can do it with one instrument I'm not going to do it with two or three and if I can do it for five dollars I'm not gonna do it twenty five dollars but the one thing I won't ever sacrifice is outcome. So it's all about trying to achieve clinical success each time and every time so the the ability to mechanically instrument the root canal system has been probably the biggest long-standing change in the twenty years that I've been doing it but more recently in the last five to ten of course cone beam for a decade I would say to my patients say if only we could see this Anatomy in 3D or we could see where this resorption goes or we could see where the inferior alveolar canal is relative to this route end that would really make a difference in treatment planning and what we might do from a retreatment perspective or a surgical perspective and now we have that. Right we can get that information in each case every case or when we think it's clinically relevant when it's going to potentially improve outcome I'm gonna learn something where I'm going to be able to better predict an outcome for my patient. So those have been the two really nice things that have have occurred I'm and and we continue to evolve you know we're on the cusp of the irrigation revolution that's what comes next. So when we look at overall success rate than endodontics we've done well right our success rates are high could they be better I'd like to think they could be better the one thing we've not been able to do over the last 20 30 40 years is deal with micro anatomy within the root canal system. We can clean and create a very dense white line within the main canal but that may not be everything that determines success, success may ultimately be determined about how clean we get the microAnatomy and I think we're knocking on the the cusp of that irrigation revolution.
Howard: and what percent of the bacteria, fungi, micro organisms are mechanically removed and what percent of all those organisms is still there and would only be and have to be gotten with irrigants?
David: Yeah it's hairy it's scary when we talk about these numbers if you look at repeaters classic study on instrumentation of the root canal system about 30 percent or just over 30 percent of the canal wall is untouched by mechanical instruments you can translate that into about 30 percent of the biofilm it is left behind. So if we don't have an adequate way to clean in to the main canal irrigate into the micro anatomy we are not going to be able to remove that biofilm and those microorganisms from the canal system. You know the old-school concept was that instruments would would shape and irogants would clean and that would absolutely be the case if the bacteria were simply free-floating in the canal but they're not, there in a firmly attached biofilm to the canal wall and if we don't physically disrupt that biofilm we're not bringing those bacteria out.
Howard: So you've said a couple times already that there were at a cusp of revolution of irrigants why do you say that?
David: I hope so.
Howard: What do you see around the corner the things that irrigation is changing?
David: Well we've had in the last several years we've had some technologies and endodontics that have evolved, one of them is the endoactivator this is a very simple and straightforward way of moving irrigant around within the root canal system after a creating final shape. Photon initiated photoacoustic streaming was a light source used to disrupt biofilm, they've gone by the way a company named Sunendo has purchased the pips the photo photon initiated photoacoustic streaming and sort of shelved them and the Sun Endo folks are using sound a sound energy and a eight minute flush of sodium hypochlorite and EDTA within the canal system with much smaller shapes than we would traditionally create doing endodontics with four and oh six tapered instruments and and showing some compelling results now that's not a technology that I've yet incorporated into my practice but I have several colleagues that have from my perspective I'm a bit conservative I still think it's an unproven technology but I hope it can do what they say it can do because I think it would have the ability to transform what we do and ultimately yield a higher success rate.
Howard: People have been talking about lasers, do you think lasers will ever be a part of endodontic canal cleaning?
David: Well they sort of have been and they've sort of come and gone in the past. Delivering an effective light source deep within the root canal system and then into the microanatomy I think is the challenge so I'm not sure that the that the light source is the way to go the sound energy and creating the acoustic stream that Sunendo is going after I that makes some sense. There's also some I think very compelling research things that not yet hit the the marketplace one of our colleagues in Toronto is doing some very interesting work with nanotechnology in order to be able to deliver irrigant truly into the micro anatomy within the root canal system and I think that is potentially a very transformative technology, this is something that's still in the laboratory setting it's not something that has evolved yet into the clinical practice and that's why I say we're sort of on the cusp of that revolution we're not there yet but I think this is a very active and important area of research in endodontics.
Howard: My homies get mad when someone's saying they do a composite and a bonding agent but they don't mention the bonding agent you know, you lose a lot of things I know other thing when when you start a root canal do you start with hand files if so which one and how far do you hand file your mechanical glidepath before you switch to 300 RPM nighttide and what file are using?
David: Yeah so I have really evolved tremendously in how I create a glide path now compared to what I used to do it used to be significant hand filings ten file 15 file 20 file but then 15 and 20 these are stiff files and that's a lot of work you know for a lazy guy like I am I don't want to do that much work because I don't need to I used to have to do that I don't have to do that anymore because the quality of the metal will allow me to simply take a hand file and it sounds crazy when I say this to people but the majority of teeth that I treat I could treat with a ten file it doesn't have any flutes on it, all I'm really using the 10 file as is a gauge where where can I comfortably put the 10 file because that will allow me to know where I can then put a rotary file if I can put it you know if I have a 20 millimeter tooth and I can immediately put a 10 file 15 millimeters into the canal and I haven't bound the file I haven't met any resistance I know that I can comfortably take a rotary instrument an orifice opener. So I use a 2008 vortex orifice opener if I can take that instrument past the dentin triangle and open up that shape when I put that 10 file back in it's not going to bind anymore at 15 or 16 it's going to continue to travel to the apex because the apex is bigger than the ten. So if I travel into the canal with that 10 file I haven't used it I'm not pushing it I'm not pulling I'm just gauging I will then go with a wave 1 gold glider, waveone gold glider which is of 15 at the tip and that's a reciprocating motion and I will take that 1 millimeter short of where resistance with the 10 file and by alternating the 10 file and the waveone gold glider I can make these incremental steps in to any and all canal anatomies irrespective of size shape or curve because the apex is always going to be bigger than a 10 file.
Howard: So Waveone that's DENTSPLY Sirona and actually there endo division, you like ben jonson company Tulsa Dental which is now owned by Dentsply which in married Sirona is that your key rotary file Waveone?
David: So as an endodontist you know in cases on a referral basis it's like anything in biology the case that I see the cases that I see in essence make a bell-shaped curve okay there's a bunch of them that fall into what I would consider standard molar root canal anatomy and for those standard anatomies where I can fairly easily make and recreate the natural glide path I'm gonna do waveone gold instrumentation to create the final shape because again it's a single-file reciprocating system it allows me to be efficient I don't have to try to reinvent the wheel I'm not using seven or eight instruments to get the end result but again none of that matters all that matters is outcome but for those more straightforward cases that's what I'm going to do in the cases that are more complicated where I need multiple files in order to sort of sneak up on the shape because it's just a little smaller a little longer more curved whatever it might be or a combo of these things then I'm going to use a file system where I need maybe two or three instruments to create the final shape and in that scenario I tend to gravitate towards ProTaper next and in the most complicated root canals smallest longest most curved they're really weird and wild ones I'm gonna use vortex loop which is oh four or oh six taper fifteen to fifty in size 500 rpm but now I'm gonna be talking about six five six seven instruments to create the final shape, so it's a more demanding technique because the anatomy that I'm treating there is more demanding how you know but but it's gonna be a much smaller number of cases we're talking about a couple standard deviations away from that at part of the bell-shaped curve.
Howard: and where did they get the name vortex blue where does that come from?
David: I don't know where the vortex comes from but the blue comes from a made oxide there that forms on the outside of the metal this is all post grind heat treatment metal which basically means that after the nickel titanium blank is filed into the appropriate shape for vortex blue it's going to be a four taper or O six taper there is a series of heating and cooling treatments that are done these are all proprietary and an oxide layer will form on the outside of the metal in the case of vortex blue it happens to be a blue color basically what the manufacturer is doing is looking at the design principles we're talking about a 500 rpm standard taper not variably tapered instrument like a wave one gold, so just a traditional four taper and they're looking at what metal will work the best in that file design a 500 rpm oh four taper and they're in essence marrying the metal to the file design which is designed to then increase our safety factor for clinicians to have a more cyclic fatigue more flexible yet efficient cutting instrument out of the package compared to what we had been doing with first and second generation nickel titanium.
Howard: Well the definition of vortex a massive whirling fluid or air especially a whirlpool or a whirlwind we were caught in a vortex of water synonyms whirlwind cyclone whirlpool black holes even one. So which one of those words do you like the best for vortex?
David: A whirlpool.
Howard: Whirlpool, so when you're what percent of your practices retreats?
David: I'm lucky in Madison Wisconsin I get to work with a group of a very skilled clinicians maybe I get some of the credit for this because we've done a lot of work over the last 20 years of helping my GP colleagues pick the winners right what ones are they gonna handle what ones are they gonna do well what one should they send out, what that's done is it's kept my retreatment rates low historically my retreatment rate is about 25 to 30% many of my colleagues around the country 50 60 75 percent of what they did in their day is retreatment and one of the reasons I do this stuff one of the reasons I put content out one of the reasons I go out and teach and talk and one of the reasons I allow people into my office to see what I do is to keep that number down and want that number to be as low as possible for everyone.
Howard: Does that mean your going to build a course on Dentaltown some day?
Howard: I'm telling you they love it, we've put up 400 courses their all ADA AGD approved and we're coming up on a million views then they just sit there on their iPhone I mean even during games I've gotta so the other day he doesn't even care during a football game those commercials because he instantly starts not checking is his email a smartphone course on that but that is so cool that by working with your value chain you're referring dentist that you've lowered the retreatment rate but when you do even at 25 percent when I think the 4,000 endodontists and you just looked at insurance billing it would be well over half of retreats when you even though yours is only a quarter what do you think causes most of the retreats?
David: By powering away the most common tooth that I retreat is the maxillary first molar and by far and away the most common reason for treatment of that tooth is the missed treatment or inadequate treatment of the mb2 canal.
Howard: Yeah and do you think that's because they were looking at it do you think they just weren't looking for it or is a two-dimensional radiography instead of three-dimensional CBCT?
David: Some of it is simply not looking, I think that's the the exception rather than the rule it's tricky okay where I was taught to look for it and where it actually exists are not one in the same okay I was taught to make this triangular access opening from the mesial-buccal line angle back towards the PAL along at the mb2 was gonna live somewhere in that line and that can be the truth but that is not the rule okay from my perspective the mb2 Canal can live straight lingual to the main mb canal and if you take a bunch of maxillary molars out and you flip them over and you look and see what's actually the most mesial portion of that entire tooth it is lingual wall of the mesial-buccal root so many times the env2 is actually more mesial than the main Mp it is often times sub popol floor so you have to be willing to dive into the floor a millimeter or two to go find it and it can be very close to the main entity or it can actually be very far lingually place almost to the palatal orifice. So it's anatomical variability I think is what really leads to many folks not finding or successfully treating and it really goes back to what we what we all learned in dental school never touch the Popol floor but if you're gonna find the mb2 you have to you have to be willing you have to know where to look because there's a road map that are telling you where to look and you have to be willing to do it.
Howard: So then what would be the number two tooth?
David: Number two is the mandibular first molar and that's going to be distal roots. So that distal root is the the conception is that it's a single root from Mora fast apex and if it is which it often is it will be broad in the buccal lingual dimension but what many clinicians will do is create a white line and I'm very opposed to the white line, now I want beautiful white lines in my root canals but more importantly I want clean canals before that beautiful white line goes in so if it is a broad buccal lingual canal space and they simply plow down the center without disrupting biofilm around the periphery it will create a dense white line on the fill but it's not clean. So in essence you almost have to treat that distal root of the mandibular molar like it's three canals, getting that buccal portion getting the lingual portion getting the distal portion and there's quite a bit of anatomical variability in the distal root as well so many times to canal orifices that join to become a single canal at the apex but oftentimes one that branches deep so the wishbone shape. So we make that access in create that shape down and really have no idea that it is branched in the buccal 1/2 so it's really again it's the same issue it's bacterial left behind.
Howard: Okay so then I'm going to flip it around she's just graduated old school she would so what is the easiest tooth to do a root canal on?
David: The easiest tooth in the mouth to do a root canal on is the single rooted single canal maxillary central incisor in the forty year old patient that hasn't had a trauma. So the pulp canal is the size that mother nature meant it to be.
Howard: What do you think is out there that miths dentists believe in endo that just aren't true?
David: Well III think I see a lot of clinicians showing me cases and showing me white lines they see a white line on a radiograph and it is beautifully shaped and it goes right to the apex and the length control is exceptional and yet it hasn't worked and they're of the misconception that the white line is all that matters and that's really it's important but it's really a reflection of the shape and hopes then ultimately the cleanliness that was created in the root canal system. If we look at our if we look at our literature and dive into it you can make an argument that proving gutta-percha in teeth although we understand the importance of it as it relates to seal and prevention of bacterial ingress you can really make an argument that the sealing of the root canal system is not very important part of what we do, it's all about the removal of bacteria so I think the common misconception out there is that if I get a white line to the bottom everything heals and that couldn't be further from the truth.
Howard: So what was the easiest tooth and you describe that nicely for people that are just out of school help them with case selection what would should they stay away from what what what will they do they might think of me oh this is a good molar to start practicing on not yet this might be the worst molar to start practicing on?
David: Yeah well I think any tooth where you can see the chamber straight away I think if you haven't done 30 or 40 or 50 root canals in your lifetime and you can't clearly see the pulp chamber I think you need to stay away from that tooth. So that would exclude teeth in the molar region that are restored with crowns where you can't adequately assess the size of the pulp chamber now you can potentially get by that with the bite wing angle right something as simple as taking a bitewing looking to see where the chamber is can I see chamber if so how far down is it from the occlusal surface and if so how far do I need to go in to get into that pulp space and where can I go. If I see chamber seven millimeters down and I'm accessing that tooth and I get that in five six millimeters I know I have work to do but if I get down seven millimeters and I haven't found the canals I know I need to go buccal lingual or mesial distal and then I also can get from that bite wing angle an assessment of hey is eight millimeters nine millimeters ten millimeters where's the fur keishon floor where are bad things going to happen okay. So I think they need to be able to see the the chamber, the other things that I think are imperative you have to have a good angled preoperative radiograph I'm not one that insists on a bunch of radiographs I just I want one well angled radiograph to look at anatomy and try to assess in two dimensions the curvature of the canals. Right how much curvature is there is there a fast break in the canal system do I see something in is there anything in that radiograph that suggests the anatomy is going to be a typical. Okay so that said before I treat a tooth I assume that every Anatomy I'm going to encounter as a typical and I'm never surprised.
Howard: So I want to know how can I get one of those shirts, sit up straight so they can see on YouTube it says I'm sure a obtr advancing endodontic education and that is a website to obtr.com Do you sell that shirt on your website?
David: I don't nobody seems to want any of the schwag except you Howard but the good news is we can get you one.
Howard: Really, do you have 3XL?
David: That might be a special order.
Howard: I'm just kidding, I may be fat but atleast im short so you know I can still fit in those XL's. What if there's one thing I can't even get my hands on after 31 years is what the hell does standard of care of me I mean it just there's more definitions of standard of care than there are people and how can any endodontic how can any general dentist do a standard of care root canal if he doesn't have a CBCT and the endodontics reused them or he doesn't have a microscope you know or I mean can I be a standard of care general dentist doing a molar endo if I don't have a CB CT and a global or Zyce microscope?
David: You can it becomes a little more difficult, so when we look at equipment tools and how they relate to standard of care really the only piece of equipment in endodontics that is the standard of care is the rubber dam. When it comes to the microscope when it comes to cone beam when it comes to any of the irrigation adjuncts that we've talked about these then become maybe considered best practices or state of the art but the bottom line is the only piece of equipment that is standard of care is the the rubber dam so the bottom line is you don't need a microscope to be able to enter into and treat for canals you don't need a CBC to know that those four canals are there are they gonna help you yeah they're gonna help you okay. Me personally I couldn't do an endodontic procedure without the use of the surgical operating microscope can I do endodontics without the use of a cone beam yeah because I did it for a whole long time so I don't have it I need it as a crutch does it make my life easier absolutely did it improve my success rates I think it probably does it certainly in some cases it's going to so when it comes to standard of care I think it's just important for that for the our GP colleagues to understand that if I was doing a crown my crown would need to be as good as theirs and I can't do a crown as well as they can because I don't do it right that's not what I do. So when it comes to standard of care when folks are treating cases endodontic lee they need to be able to get the same sort of end results that we're getting as endodontists right and and I'm not naive you know eighty percent roughly we can argue the numbers some folks say it's a little less than that some folks say it's a little bit more than that but roughly 80 percent of the approximately 20 million root canals that are done in the United States each year are done by the GPS and I just want everyone to do a good job so that it doesn't reflect poorly on me. You know I I go to parties and people ask me what I do not have to tell them I'm I'm a tooth plumber because if they find out that I do root canals as a you know for a living they're gonna tell me about the worst experience that they've had in their life or the worst experience that their aunt Mary Jane had and that's just not how it has to be that's how it used to be okay so yeah that's where I'm at with that.
Howard: Well when you hear that story you just keep looking at me I'd say did you die did you die but I know some of them are gonna say well what if they use an isolate?
David: Well I have a very simple answer to that question it's one of the more common questions that I get when I am talking with my GP colleagues is an isolated rubber damn well the answer is no the standard of care is the rubber dam and isolate is not a rubber dam and isolate is a nice to light so it's closer to the truth than nothing but it is not the standard of care.
Howard: Yeah I don't understand why they dont use a rubber dam and if you don't like placing them then have your assistant place them, numb up the tooth do a hygiene check make someone else place it but don't you think that you can do a root canal much faster and easier with the rubber dam?
David: Well I absolutely can because it's the only thing I know and I don't know any endodontists that would disagree with that. So it's not like you know it's not like there's a handful of us out there is true believer so this is us this is us as a specialty. So it truly is the standard you know a lot of things can happen files can brake, preparations all sorts of crazy things during the procedure but a file getting away and being aspirated swallowed that's not something that you can recover from right and it's and it's preventable, it's preventable not some of the time but every single time the the rubber dam so there's a safety factor there over and above the biological factor of we're gonna get a better outcome with the rubber dam because we're not going to be constantly recontaminate in our work filled with bacteria.
Howard: and so I know what their thinking, their thinking which CB CT and which microscope did you get. Let's start with microscopes. did you go global out of St. Louis or Zyce out of Germany which one?
David: So I have global scopes I've always had global scopes and the reason is because when I trained at the University of Michigan that's what I use there and I felt comfortable with it straight away. From my perspective earlier on ten years ago the quality of the optics and light source in the Zyce well actually I think a little bit more superior than the global but there was still that comfort level that I had there and now I think the quality of the light source and the optics between the two has that gap is narrowed. So bottom line is I don't really care what the manufacturer is as long as there's some level of illumination and magnification it doesn't even need to be a microscope quite honestly, I think a lot of my GP colleagues I see some really good endodontics coming from folks that are using loops and a light source for ax 5x but they're it's imperative that they have the light source right if you're going driving at night and you're gonna kill the headlights and drive in the dark just in the dark by feel with binoculars in Wisconsin you're gonna hit a cow now you're gonna be off the road before you know it so you gotta have a light source as well so a light source in some level of magnification should get you to the truth.
Howard: One time for Christmas I got him the Zyce binoculars I think the coolest thing you can go outside before the Sun's up you know say you're elk hunting or whatever it is the coolest thing those binoculars I mean everyone he takes binoculars to a game sometimes I'll say can I look through those and you look through them it's like why'd you even bring these and but those I don't know if global makes binoculars but if you did a hundred root canals what percent of the time would you use your microscope?
David: 100% of the time so once the rubber dam is placed and even sometimes with the the use of the microscope the rubber dam will be placed from the time the rubber dam is in placed until the time the temporary is in place or the tooth has some sort of coronal seal I'm looking under the microscope the entire time.
Howard: At what X?
David: Somewhere 4 X 5 X and their differences in one room I have a 4x scope with the lowest step and then one a 5X I can go up to 10 12 18 20 but those those higher magnifications those are looking for cracks those are maybe doing a little bit of post removal those are our magnifications where the depth of field is simply too shallow to work so the great great great majority of the work that I do is in the 4 5 X range okay and that is attainable loops and a light source.
Howard: Same question for CBCT if you want brand and if you had a hundred root canals what percent time would you get a three-dimensional picture of that tooth?
David: Yeah so some colleagues that so I'll answer brand first I'm using Care stream that I have a bunch of friends that use J morita and I can sort of see a few differences in the huge scan and quality between the two. There's also a significant difference in cost in the in the dense strop to to get the equipment so from my perspective I think they're very very similar when it comes to percentage of cases I have some colleagues that are using cone beam in every single case and their rationale is I can learn something I have a tool why wouldn't I use that tool I don't know what I know unless I ask the question and I get that I understand that however from my perspective I because I've done for a long time without I don't feel that I need it in every case I take it when I think it's going to be a benefit to me and or the patient retreatment resorption x' surgeries almost a hundred percent of the time. I'm a big fan of an intraoperative cone beam if I don't have a cone beam and I'm treating a maxillary first molar and I'm in that tooth and I've treated the three main canals and now it becomes mb2 time and I'm doing a little bit of search and I'm not that search is not giving me another canal and yet I suspect there's another one there I a choice I can take away tooth structure or we can put the breaks on and I can get a cone beam and by putting the brakes on and getting a cone beam I find out that there isn't another canal there and I haven't then sacrificed any tooth structure in order to answer that question. So for me on a percentage basis somewhere between thirty and forty percent.
Howard: Nice and how many different irrigants do you use?
David: So I use em hypochlorite I use five point two five percent sodium hypochlorite so that's stock out of the bottle I use that early often during the procedure because we understand that there's a volume of fact to sodium hypochlorite and the effectiveness of diminishes with time so I'm constantly turning that over in a molar root canal four canal molar root canal I'll typically use 5 5 ml syringes throughout the the case when I'm done doing the instrumentation and that's when the sodium chloride is basically done I will do a final rinse with qmix which is a chlorhexidine and EDTA combo irrigant and at that point what we're going to be getting is a smear layer removal and a secondary disinfection simultaneously and that may be a little bit more kind to the dentin than the traditional sodium hypochlorite EDTA sodium hypochlorite regimen that we used for so many years.
Howard: There's a lot of when I lecture in Cambodia, Vietnam, Indonesia, Malaysia, they always asked me this how come Americans don't use hydrogen peroxide what would you say to our Asian listeners it's huge in China it's huge in Southeast Asia what would you say to the guy who asks that?
David: Yeah so the bottom line so for me the the prototypical irrigant would fulfill a variety of tasks the ideal irrigant would kill bacteria, it would dissolve tissue, it would be as kind as possible to the dentin substructure so that we're not changing the biochemical nature and makeup of the dentin and from my perspective when we look at what hydrogen peroxide is going to do against what sodium hypochlorite is going to do when it comes to killing bugs and dissolving tissue that's going to be by far and away as a superior irrigant. So I don't think there's any wrong with hydrogen peroxide I just don't think it's asked effective as other regiments.
Howard: So if you did a hundred molars what percent of the time would you use hydrogen peroxide?
David: What percent would I use hydrogen peroxide? I don't.
Howard: Okay and what percent of time would use a chlorhexidine gluconate?
David: So I will use chlorhexidine as my sand alone irrigant replacing sodium hypochlorite in one clinical scenario that clinical scenario is typically a mandibular second molar where a lingual cusp or two is gone and I'm not convinced that I'm going to keep every drop of sodium hypochlorite in the tooth especially if it's an irreversible pulpitis scenario. If it's a necrotic pulp scenario I may still consider using sodium hypochlorite because I know one thing for sure after doing this for twenty years people do not like how sodium hypochlorite takes if I don't if I know I can't control every drop of it I know I don't want to drink it I know my patients don't want to drink it.
Howard: Unless their russian or Irish where they'll drink anything straight.
David: and they don't even care then they said thank you can I have one more.
Howard: and when you're irrigating what what percent of the time to use the endoactivator system kit that you mentioned earlier?
David: So I use so I use an endoactivator in virtually every case that I treat irrespective of Popol diagnosis so irreversible pulpitis cases and chronic cases is retreatment cases and there's an irrigating regimen that I go through when I've created the final shape in the root canal system I will give a fresh 5 ml rinse of sodium hypochlorite this is the deepest the totem hypochlorite is going to penetrate into the canals because I've now created the final shape and at that point I will use the endoactivator the idea behind the activator there is to create turbulence within the canal system and bring out biofilm and debris I will pull out that sodium hypochlorite and there's a water rinse that's done and then the qmix will go in and that qmix is activated so each canal gets about a minute of activation 30 seconds of sodium hypochlorite 30 seconds of qmix.
Howard: Another huge debate on dental town and and again it's hard to tell what's myth what's going on but to one step or two step and a lot of the debate focuses on if there's periapical pathology so my guess would be one step would you two stop and I'm not talking about a country-music line dance.
David: That's good because I don't dance but I'll ask you a question I'll dance around the question by asking you a question, do you have your appendix?
David: Do you know anybody that doesn't?
Howard: Do I know anybody I know I mean patients...
David: Well okay well we'll go hypothetical on it then if someone was having their appendix taken out how many steps do you think they do it in?
David: There you go there's the answer to the question okay but what's the difference from the biology perspective the difference is when the appendix comes out boom can see it it's gone okay we don't have that same metric what limits us. From an endodontic perspective is our in our inability to measure the absence of bacteria within the root canal system right so you can ask that question are all the bacteria gone and the answer is we don't know that's the honest answer okay. So when do I single visit versus multi visit root canals it's I'm pragmatic I'm a clinician so some of it has to do with what day of the week it is. I am more likely to place gutta-percha into a canal system on a Monday than I am on a Thursday or Friday if there is a necrotic case with a mild amount of swelling but the real real deal for me the canal needs to be dry okay if the canal is not dry it is not going to see gutta-percha right and what I've learned from my travels and travails here over the last and full of years we can't even agree on what dry means okay. I think ty is you can put a paper point in you can grab another paper point put it in and it's still dry, other folks define dry as well I took the paper point out and I immediately stuff in piece of gutta-percha and there wasn't enough drainage to push it out so that must have been dry okay. So we don't agree on that and that's and that's okay there that you know again this is the practice of endodontics there's no right or wrong answer okay but really from my perspective if the canal is dry if the canal is clean if I can do my irrigation protocol it is most likely going to gutta-percha irrespective of diagnosis irreversible pulpitis necrotic retreatment probably doesn't matter that said a little bit of swelling earlier in the week more apt to get gutta-percha than something later in the week because that you know no one likes the the weekend call I'm pragmatic.
Howard: Here's another emotional question, some people you know your always are running into your endodontics at your study clubs your your study meetings and things like that and some of them want to can't use like a guttacore a gutta-percha with the carrier but sometimes they feel bad and people that maybe it makes it hard to retreat and they're endodontists isn't gonna like them if they're using agutta-percha carrier so I'll just be brutal what do you think a guttacore and what do you think of gutta-percha carriers in general and does it make your life more difficult or is it just a non-issue?
David: Let's go carriers in general first and then I'll go proc specific the bottom line is if you get a root canal system equal it clean across the board irrespective of Popol diagnosis you have you know you're treating four teeth in the same patient and you won with a rigid carrier based operation like a thermo fill one of the guttacore one with a silicone one with a down pack back bill like endodontists might do you're going to see equal results okay the cleanliness is what matters. The problem that endodontists have with some of the carrier based techniques is that a stiff and rigid carrier could be placed into the canal system in essence creating a very dense white line in an optical illusion something that looks like a significant amount of instrumentation was done even though it wasn't an a rigid plastic carrier then becomes in it's inevitably going to be retreated or a surgery is going to be done and taking those carriers out and or doing a surgical procedure it becomes difficult. So as a whole endodontists are not too fond of carrier based operation that said when you go to a carrier base like guttacore, guttacore is a little different it's all gutta-percha so the carrier itself has gutta-percha if we look at the amount of time required to remove a guttacore carrier against a Down pack backfill fill or a rigid carrier base the thermal fill it's actually easier to remove. So I'm not one that's anti carrier I use carriers in my practice okay there are times when it is impossible with some of the anatomies that we treat to thermoplasticized gutta-percha deep within the root canal system using a traditional downpack backfill technique, the only way to carry warm gutta-percha to the apex in those scenarios is going to be with the placement of a carrier based operation. So the bottom line is there's nothing wrong in my in my view with a carrier based operation as long as that canal is clean prior to the placement of the carrier but the nice thing about a gutter is that if you don't have the shape it won't go because it's brittle like gutta-percha it will break on the way in it will not get to the apex.
Howard: I want to ask you another bizarre question this is dentistry uncensored there are dentists that never ever place a post in a molar or bicuspid. I mean they have a place to post one time in years there's other ones who play suppose in every molar root canal they do, how do you explain such a huge variance okay I didn't place with last year to every tooth got one last year?
David: Yeah it's interesting, it really becomes a clinician du jour type of decision making tree I have some my refer partners that irrespective of restorative status want they maybe put a brand new crown on this thing and everything is great but it ended up needing a root canal and you want a post sunk into the tooth post base so that they can place the the posts and others to your point they will anything and everything to never use a post and we see everything in between. So from my perspective there's some changing and emerging literature in the endodontic community about the placement of posts whether we're talking about a fiber post dual to your kind of system any post system where we're going to remove tooth to place the post unless it's absolutely necessary to retain the core is going to be diminishing the overall strength of that tooth. So you know the way I look at this the post is used to retain the core, the core is used to provide stability for the crown therefore if we can retain the core without the use of a post I would avoid using a post.
Howard: So here's a bazaars question you've probably ever been asked I hope I win the race but...
David: You'd be surprised.
Howard: Well I did four or five podcasts filmed on location in Tokyo another dozen in London more in Paris where they have a government healthcare system kind of like we have Medicare for over 65 and then each state has Medicaid for poor but in their countries the they only give about a hundred dollars us for a molar root canal and those guys tell me off the record they wouldn't say it on the podcast but they tell me off the record when they're drinking beer that they have to place a post in every canal because they the benefit for the post is equal to the benefit of the root canal. So if you were lecturing right now to dentists in Tokyo London and Paris and said I don't care what you hey I either gotta go bankrupt or quit or what do what some of their colleagues did which is quit doing molar endo and extract the tooth into an implant because the implants not covered so if they do the molar root canal and Tokyo London or Paris it's about $100 u.s. but if they extract it they can do a $1,500 implant which would shouldn't make everybody really think about a these insurance plans but if you were lecturing to a dentist in Tokyo London Paris said look dude for insurance reasons I have to place a post in every canal which one would you recommend which one first do no harm. Which one would be the least harmful?
David: Yeah so it would be a post system or no to structure was removed so we have enough shape just built into the natural canal. So a fiber post dual cure composite type system would be what I would definitely recommend the you're going to get...
Howard: Name a brand.
David: Couldn't do it have an ever placed one, you know that's the thing about the U.S. how we do this, there are some some of my colleagues are doing the root canal plate in the post core and even sort of roughing in a crown preparation and sending the tooth back to there restored a colleague whereas in other parts of the country if we did that my GP's would be very unhappy with me because that's sort of their thing it's pretty straightforward for them to do so it becomes a nice procedure for them very predictable. So yeah it would be a fiber post with the dual cure kit, can't tell you a name or a brand at all. There's a bunch of them out there though.
Howard: So back to the post answer you said that when it doesn't remove tooth structure there's a lot of debate I mean there's some dentists that like that the 0.08 taper and then the other dentists are in those cases and saying dude that's too much that's too much destruction you're waking to the tooth how much taper is too much taper and what size taper do you like?
David: Well the the the most important piece of dentin that determines how that tooth is going to do long haul from a fracture resistance perspective is the pair of cervical dentin so we're talking about a couple of millimeters above the level of the crustal bone and a couple of millimeters below the level of the crustal bone. So most of the instrumentation that I do is going to be variably tapered so it might be oh six at the apex and that taper is getting smaller as we come up so I don't really like to talk about taper as much as maximum fluted dimension, okay. So the the maximum fluted dimension of a waveone gold primary for instance you know at D 10 D 11 is going to be just over 90 okay so if you think about typical gates glidden's back in the day 50 70 90 it would be the size of a number 3/8 Glidden exactly guys up I really don't want it to get any bigger than that, so most of the instrumentation that I do is going to be or some very it's variably tapered but most of the apical instrumentation that I do if it's waveone gold primary that's 25 at the tip so the master apical file dimension 25 and that's 07 papered and that's from D0 at the tip back to D3, three millimeters from the tip so it's 49 at D3 but if we think about some of the classic instrumentation studies that looking at the the ability to deliver irrigant deep within the root canal system they wanted something bigger than a 30 sum between 30 and 35 well one millimeter back from D5 with seven taper is 32 okay so all of that math makes some sense from my perspective.
Howard: So there's been a lot of changes lately in sealers you know gosh 30 years ago is grossman cement a ceramic series where you're thinking with sealers these days?
David: Yeah that's a great question I you I'm currently using a AH+ sealer okay. So it's a resin sealer I've been using it for years and that's why I'm currently using it I'm using it because I've used it for years, it is in my hands predictable and has withstood the test of time. Some of the bio ceramics very compelling from from my perspective but I do have some issues with them as well. The set time of the bioceramic sealers can be exceptionally long there isn't a sealer in the world on them on the market in the unset stage that doesn't have some level of inflammatory reaction associated with it. So all sealers in the unset stage are pro-inflammatory if that sealer set time is extended and we're talking about maybe over a hundred hours that's a long time to be eliciting an immune response and that's neither here nor there because that that may be the exception rather than the rule. One of the main tenets of a sealer or an operation technique from my perspective has to be retreatability we all like to think our success rates are going to be 100% but they're not and if we have a sealer that in essence bonds to the canal wall and we then go back in to remove the single cone of gutta-percha and that high volume of sealer there's going to be no way that we're going to be able to remove that sealer and in essence disrupt the biofilm that leads to the failure in the first place. So it really becomes an untreatable scenario.
Howard: We went over an hour and I still have a few questions left can I go over now can I go into some overtime with you?
David: Keep going, keep going.
Howard: Okay well there's basically two types of people who do root canals theirs either the apical barbarian who wants to get all the way to the bottom and a sealer or there's that little pulp lover who always wants to stop shy and have the apical, are you would you say you're more of a pulp lover or an apical barbarian?
David: Well I'm not a pulp lover okay because I'm a root canal person I'm a endodontist I think all the pulps need to be out of those teeth. You know that's what keeps me busy that's it when it comes to the puff of sealer this is also something that's very regional you know you get into the into the Boston area and they they have this no puff is big enough right they can't see enough sealer out the end you get into Southern California and if you don't have a puff of sealer out the end they think you're short, so I'm not there but I don't mind seeing some sealer out the end what I really want is the maximum amount of gutta-percha that I can within the canal system I want to use the sealer to get into the micro anatomy and every now and again I get some puffs of sealer here and there and a lateral canal here and there and that's all well and good and when I see these puffs of sealer you know mid route or an apical Delta you know I give myself a little pat on the back and I walk out of the room and wonder well I see three or four accessory canals in this tooth I wonder if there were four five six right we have no idea.
Howard: So I would I mean I just again I know several dentists that if they did a hundred molar root canals every single patient we get Pen VK and twenty vicodin and then I know other dentists who just are outraged by that and I obviously see a big shift. I remember I got out of school thirty years ago the health care providers where the bad guy is because grandma's dying a cancer and they wouldn't give her any pain med and why is she in pain she's going to die anyway and and so people started losing him now with a bad guy again because we prescribed so many opiates that now were a blamed for a lot of the addiction and then same thing with antibiotics people are getting immune to antibiotics which is hard to explain the concern about antibiotics when 90% of all antibiotics are used in raising and put in our meat supply eat cows chickens pigs it's like if they seriously won to get serious about antibiotics the first thing they do is remove from the farms but again I'm gonna hold your feet to fire, if you did a hundred molars what percent would get antibiotics what percent would get opiate?
David: Well hundred molars for me is about a month's time so I do somewhere between 25 and 30 molar root canals in the in a week as an endodontist and in that weeks time I will prescribe an antibiotic or two and a pain medication or two okay so for the hundred we'd be talking about less than ten percent. From a pain management perspective I've never been one that's just that's prescribed a whole bunch of narcotic containing pain medication because it simply doesn't work as well as some of the other regimens that we have a combination of ibuprofen and acetaminophen can be extremely effective. Will I prescribe narcotics absolutely if someone comes in and they not slept you know the night before and I think they're in front of the rough night or two they're probably going to get pain medication and I said probably because it's not in everything and that's why I you know for the folks that you describe that prescribe to to everyone and for the folks that prescribe to no one and everyone in every I respect that I understand that I don't know that there's a right or a wrong answer okay so for me it really becomes on a case by case scenario when it comes to antibiotics it's pretty straightforward for me if the canals are if there's a drainage into the canals if there is swelling certainly if there's fever lymphadenopathy any sort of systemic implication they are going to get antibiotic. The best way for my perspective to treat these infections that we're dealing with in the root canal system is to clean and shape the canals right if I have a sliver in my hand and there's infection around that's the best way to get rid of that infection is not with an antibiotic but by removal of the sliver. Now that's an in endodontists office we have the luxury of being able to very efficiently clean and disinfect root canal systems in a fairly rapid manner and it's what we do and it's what we're set up to do for the GP who may not be able to do a complete debris and of the root canal system is an antibiotic a pragmatic way to offset some of the swelling that might exist and some of the discomfort that might exist absolutely right so then again it becomes a case-by-case basis but for me I'm relatively conservative.
Howard: My insurance friends due to the dysfunction between the insurance companies and the dentist they they won't ever give me stuff I can publish and post but they're always showing me stuff well one of the things that sticks out to me the most why did the the number of apliclectomys plummet over the last several decades? Why do you think the number of apliclectomys you guys are doing has been drifting downwards for decades?
David: I think it's multifactorial I think we have another option you know back in the day there were the options to hang on to that tooth that tooth out and maybe not the restorative options available. Now with the ability to place an implant into many of these positions I think in many instances we're not even given an opportunity to discuss risks and benefits to patients I think a lot of times that's happening in the gp's office and they're saying hey that tooth has had a root canal we've done what we can do it should probably come out at this point and it's interesting that you ask the question because when we look at our surgical success rates we really need to make a distinction between micro surgery and pre micro surgery, when we look at micro surgical success rates with the use of a surgical operating microscope and ultrasonic tips line-of-sight direct vision our success rates are actually spooky high they approach or exceed that of retreatment in many instances but yet I completely agree with you I think I've seen this in my practice the numbers of surgical interventions that I do now it's probably at an all-time low part of that is also due to the fact that our ortho great success rates are high right if our if our first time around success rates and retreatment success rates are high we don't need to go to the surgical approach.
Howard: and last question and what would you say we hear this on Dentaltown, it's a young kid he's in endo grad school he's becoming an endodontist and he's asking the general dentist on dentaltown should he learn how to place implants too, do you think ten years from now endodontists are all gonna be placing implants to or do you do you place implants, is there's anybody in your practice placing implants?
David: Yeah I don't place implants no none of my colleagues there are six of us in my practice place implants. Back in the day when we think about the introduction of a new technology into the dental realm and the placement of intraosseous implants for us as endodontists it probably made great sense right we're thinking about doing a surgery we lay that flap we see a crack in the root and how much sense would have made at that point to say all right let's take that tooth out and simply place the implant in that position but we didn't so we as a specialty said you know we're good enough here doing all of this instrumentation inside the tooth the oral surgeons and the periodontist if they wanted to start placing these implants great you know and because that's the way that it was I think that's the way that it will continue to go. Now there are certain programs where implants are being placed I'm an endodontic perspective but I don't think we're ever gonna get the numbers and the experiences necessary where I would feel comfortable saying I'm a specialist at placing implants right. I'm a specialist at doing root canals I can clean and shape a root canal system there after doing this for 20 years there I get surprised but it doesn't happen very often when it comes to placement of implants without that skill set without that experience I gotta be surprised all the time.
Howard: and you know it always comes back to I think the smartest health care economist in the world is Regina Herzlinger at Harvard University we I was able to get her on the show after a few years and she talks about the focus factor, she's been talking about that for 20 years that that people who do one thing like say you ask appendix removal the people the focus fast period and the faster they go like if your average appendix removal surgery from start finishes ten minutes and mine is 20 the guy doing it ten minutes will have a much greater success rate because they know what they're doing they're focused they do a whole bunch of volume of it and they just really get a focus factory on one thing and I've also had insurance people I was lecturing to insurance symposium in Florida this year and there's about three or four hundred people and the insurance companies and they would show me data at the bar that if they an endodontist do a hundred molars at 60 months fighters that have been extracted and a general dentist to a hundred molars ten percent have been extracted and I almost wanted to just like steal the chart and just like publish it anyway but then they would never show me anything else again but so yeah so just get focused David Landwehr DDS, MS his website is obtra.com coolest name obtra.com Man it was a huge honor that you stayed with it I can see how your window it's dark now you stayed after work for an hour to talk to my homies I really hope you make us an online CE course or an article in dentaltown someday I could listen to you for hours I think molar endo is their hardest thing, implants a lot of them would even consider learning how to place an implant but a molar endo I think the average dentists out there that's their hardest thing and it was very very fun to podcast interviews thank you so much for taking an hour of your time and coming on the show.
David: Thanks for having me, I enjoyed it I'm looking forward to seeing everyone at the Towniee meeting in Scottsdale in 2019.
Howard: Nice okay I'll see you there buddy .
David: All right thanks